liminfoJSON Formatter
Free web tool: JSON Formatter
About JSON Formatter
The JSON Formatter is a free online tool for formatting, beautifying, minifying, and validating JSON data. Paste raw or minified JSON into the input field and instantly transform it into cleanly indented, human-readable output with 2-space indentation. Conversely, you can compress verbose JSON into a single compact line for efficient network transfer or storage. The built-in validator catches syntax errors such as missing commas, unmatched brackets, trailing commas, and invalid escape sequences, pinpointing exactly where the problem occurs.
This tool is essential for API debugging, configuration file editing, and data inspection. Frontend and backend developers routinely format API responses to trace data flow, DevOps engineers validate JSON config files for Kubernetes, Terraform, or CI/CD pipelines, and data analysts inspect JSON datasets before processing. Whether you are reading a webhook payload, troubleshooting a malformed REST response, or preparing fixture data for unit tests, the JSON Formatter streamlines the process.
All parsing and formatting runs entirely in your browser using the native JSON.parse() and JSON.stringify() APIs. No data is transmitted to any server, making it safe for use with sensitive payloads such as authentication tokens, user records, or internal configuration. The tool works offline once loaded and supports dark mode for comfortable use.
Key Features
- JSON beautify with consistent 2-space indentation for readable, well-structured output
- One-click minify to compress JSON into a single line, reducing payload size for APIs and storage
- Syntax validation that detects and reports malformed JSON with the exact error message from the parser
- Error position reporting so you can quickly locate missing commas, unmatched brackets, or invalid values
- Instant copy-to-clipboard for formatted or minified output, ready to paste into your editor or terminal
- Monospace font rendering with proper whitespace preservation for accurate visual inspection
- Handles deeply nested objects and large arrays without truncation or performance degradation
- Works entirely offline after initial page load with zero server communication
Frequently Asked Questions
What is JSON and why does it need formatting?
JSON (JavaScript Object Notation) is a lightweight data-interchange format used by virtually all modern web APIs, configuration systems, and databases. Raw JSON from APIs is often minified into a single line to save bandwidth, making it nearly impossible to read. Formatting adds indentation and line breaks so you can visually trace the hierarchy of objects, arrays, and key-value pairs.
How do I format JSON with this tool?
Paste your raw or minified JSON into the input textarea and click the "Format" button. The tool parses the input using JSON.parse(), then re-serializes it with JSON.stringify(parsed, null, 2), producing cleanly indented output with 2 spaces per level. The result appears in the output area, ready to copy.
What is the difference between beautify and minify?
Beautify (format) adds indentation, line breaks, and spacing to make JSON human-readable. Minify removes all unnecessary whitespace, producing the most compact representation. Beautified JSON is ideal for reading and debugging, while minified JSON is optimal for network transmission and file storage where size matters.
How does JSON validation work?
The validator attempts to parse your input with JSON.parse(). If parsing succeeds, the JSON is syntactically valid. If it fails, the browser engine returns a detailed error message indicating the type of error (unexpected token, missing comma, etc.) and its approximate position. Common issues include trailing commas, single quotes instead of double quotes, unquoted keys, and comments, none of which are valid in strict JSON.
Can I format JSON that contains special characters or Unicode?
Yes. The tool preserves all valid JSON string content including Unicode escape sequences (\u0041), newlines (\n), tabs (\t), and emoji characters. JSON.stringify correctly handles all UTF-16 code points, so international text, mathematical symbols, and emoji all format without issue.
Is my data safe when using this JSON formatter?
All processing happens entirely in your browser. The JSON never leaves your device, is never sent to a server, and is never stored. This makes the tool safe for formatting sensitive data such as API keys, access tokens, user personal information, or internal configuration payloads.
What are common JSON syntax errors this tool catches?
The validator detects missing or extra commas, unmatched curly braces or square brackets, unquoted or single-quoted keys, trailing commas after the last element, use of undefined or NaN (not valid JSON values), comments (JSON does not support // or /* */), and improperly escaped special characters within strings.
Is there a size limit for the JSON input?
There is no artificial limit imposed by the tool. The practical limit depends on your browser memory. Modern browsers handle JSON payloads of several megabytes without issues. For extremely large files (100 MB+), a desktop JSON editor may be more appropriate, but for typical API responses and configuration files, this tool handles them instantly.